Abstract: An electrochemical sensor having electrolyte, at least two electrodes and an electrolyte reservoir in a housing. The sensor has a hydrophobic gas communication means between said electrodes, electrolyte reservoir and ambient atmosphere. An electrochemical sensor having hydrophobic communication means mounted between electrodes and extending down to the electrolyte reservoir of the electrochemical sensor. Either embodiment of the sensor can provide oxygen for operation of the sensor and a balance of pressure, without interfering or poisonous gases.

Abstract: The invention relates to gas sensors, particularly electrochemical gas sensors. The reliability of such gas sensors has been ascertained by regular tests, which involve exposing a sensor to a gas for test or calibration purposes. However, it has been difficult to provide a known quantity or concentration of gas. Another problem has been that blockage of a gas inlet has rendered the gas sensor unreliable. The invention provides a gas sensor having a self test capability and first and second electrodes, arranged so that test gas arrives at a separate instant at each electrode so as to generate two electric currents, the ratio of which currents provides an indication of the status of at least one electrode.

Abstract: The invention relates to an air/fuel ratio detection apparatus for a gas. This apparatus includes (a) a heater portion having an elongate cylindrical shape; (b) a solid electrolyte layer surrounding the heater portion and activated by heat to conduct oxygen ions therethrough; (c) a first electrode positioned between the heater portion and the solid electrolyte layer; (d) second and third electrodes in contact with an outer surface of the solid electrolyte layer and away from each other; (e) a first voltage applying device for applying a first voltage between the first and second electrodes; (f) a second voltage applying device for applying a second voltage between the first and third electrodes, the second voltage being higher than the first voltage; and (g) a diffusion layer made of a porous material and covering the second electrode to adjust transmission of the gas to the second electrode.

Abstract: Binding between two members of a recognition pair, e.g. antigen-antibody is determined by utilizing a probe which includes a piezoelectric crystal with electrodes on two opposite faces of the crystal. The crystal carries one or more metal plates which may be the same or different than the electrodes, the metal plates having immobilized thereon a first member of a recognition pair. Binding of a second member of the recognition pair to the first member, or dissociation between the two members and release of the second member from the probe, causes a change of immobilized mass which results in a change to the probe's resonance frequency.

Abstract: Electrochemical sensor for determining analyte in the presence of interferent, particularly carbon monoxide in the presence of hydrogen. An electrochemical cell is designed so that current flow resulting from reference electrode potential shift caused by interferent cancels out the current flow caused by interferent at the working electrode. Another electrochemical cell corrects for interferent concentration using the potential difference between a reference electrode in contact with interferent and a referent electrode not affected by inteferent.

Abstract: Electrokinetic devices having a computer for correcting for electrokinetic effects are provided. Methods of correcting for electrokinetic effects by establishing the velocity of reactants and products in a reaction in electrokinetic microfluidic devices are also provided. These microfluidic devices can have substrates with channels, depressions, and/or wells for moving, mixing and monitoring precise amounts of analyte fluids.

Abstract: An oxygen sensor forming a sensing element which comprises a solid electrolytic substrate of ziconia of the shape of an elongated flat plate, a measuring electrode and a reference electrode which are formed of platinum, said measuring electrode and said reference electrode being formed on both opposing surfaces at an end of said solid electrolytic substrate so as to be opposed to each other, wherein said measuring electrode has an electrode area of from 8 to 18 mm2, and said sensing element has a width w of from 2.0 to 3.5 mm at the end of the solid electrolytic substrate. The oxygen sensor exhibits excellent gas response performance, can be quickly heated and is small in size.

Abstract: The present invention provides an apparatus and methods for efficient, high-throughput electrical or electrochemical detection of biomolecules. More specifically, the invention provides an apparatus in which an independent set of electrodes is used to increase the occurrence of a desired bio-conjugation event at a test site.

Abstract: An electrochemical analysis system includes a chamber (34) that defines a fluid receiving reservoir therein. A working electrode (40), a reference electrode (42), and a counter electrode (44) is mounted to the chamber. An electrochemical analysis circuit (38) applies appropriate voltages to the electrodes and reads appropriate currents from the electrodes to provide an indication of the peroxyacetic acid concentration in a sample. The working electrode includes a glassy carbon rod (60) which is surrounded by a compressible polymeric sleeve (64) and a metal sleeve (66). One end of the metal sleeve is swaged (68) to form a fluid tight compression seal with the insulating sleeve and the glassy carbon rod. An electrically conductive thermal extension joint between the glassy carbon rod and an electrically conductive rod (70) includes a bore (72) in the conductive rod in which the glassy carbon rod is slidably received and a compressed spring (74) in the bore.

Abstract: A sensor is described for measuring the concentration of a gas component in a gas mixture, particularly a lambda probe for measuring the oxygen concentration in the exhaust gas of an internal combustion engine, having a solid electrolyte and having two electrodes separated by the solid electrolyte, of which an outer electrode is exposed to the gas mixture and an inner electrode is situated in a cavity separated from the gas mixture by a diffusion barrier. To achieve a broadband measuring of the air ratio &lgr; and a simplified construction compared to a known lambda broadband probe having a pump cell and a Nernst cell, the sensor is operated according to predefined criteria, alternately as lean operation probe according to the limiting current principle and as transition probe having a pumped reference.

Abstract: A multiple electrode includes a plurality of micro-electrodes provided on a substrate, and a wiring portion for providing an electrical signal to the micro-electrodes or extracting an electrical signal from the micro-electrodes. Each micro-electrode has porous conductive material on its surface, and the impedance of the micro-electrode is 50 k&OHgr; or less. Preferably, the porous conductive material is gold, and formed by the passage of current at a current density of 1.0 to 5.0 A/dm2 for 10 to 360 sec. The multiple electrode may include micro-electrodes provided on a substrate in the form of a matrix, a lead line connected to the micro-electrodes, and an electrical junction connected to an end of the lead line.

Abstract: An electrochemical measuring cell for detecting hydrocyanic acid is improved in such a manner that a stable measurement signal is provided after a short time. The measuring cell includes a measuring electrode (1) of sintered gold and a counter electrode (2). A measuring cell housing (4) accommodates the measuring electrode (1) and the counter electrode (2). An electrolyte is in the measuring cell housing (4) and includes sulphuric acid with an additive of silver sulphate. A diffusion membrane (5) is disposed between the measuring electrode (1) and the substance to be detected.

Abstract: A design and method for fabricating an electrochemical transducer including two housing plates, each of the housing plates being constructed of a polymer material and wherein each of the housing plates include an inner side, an outer side and a plurality of channels through the housing plates so as to communicate the inner side with the outer side, two anode electrodes, the anode electrodes disposed so as to be sandwiched between the housing plates, two cathode electrodes, the cathode electrodes disposed so as to be sandwiched between the anode electrodes and three porous insulating layers, the insulating layers being constructed of a polymer mesh and wherein each of the insulating layers is disposed so as to separate each of the anode electrodes from the cathode electrodes and each of the cathode electrodes from each other, while permitting the flow of an electrolyte between them.

Abstract: The invention is a method for the formation and analysis of novel miniature deposition domains. These deposition domains are placed on a surface to form a molecular array. The molecular array is scanned with an AFM to analyze molecular recognition events and the effect of introduced agents on defined molecular interactions. This approach can be carried out in a high throughput format, allowing rapid screening of thousands of molecular species in a solid state array. The procedures described here have the added benefit of allowing the measurement of changes in molecular binding events resulting from changes in the analysis environment or introduction of additional effector molecules to the assay system. The processes described herein are extremely useful in the search for compounds such as new drugs for treatment of undesirable physiological conditions.

Abstract: A reference electrode (1) for electrochemical measurements includes a metallic palladium-containing electrode component (3) which is covered by a layer (4) formed of or containing a palladium compound poorly soluble in aqueous media. Positioned on layer (4) is a reference electrolyte (5) which contains anions of this palladium compound in dissolved form (FIG. 4).

Abstract: A gas sensor including a housing containing at least a sensing electrode, a counter electrode, a test electrode, and electrolyte means in contact with such electrodes. The housing permits gas from the environment to flow to the sensing electrode. The gas sensor is operable either in a normal mode of operation in which potentials are applied to the electrodes for detecting when a gas to be sensed is present at the sensing electrode, or in a test mode of operation in which potentials are applied to the electrodes so that the test electrode generates a gas which flows to the sensing electrode to enable an indication whether the sensor is operating correctly.

Abstract: An electrochemical sensor (A, A′) is specific for the detection of peroxyacetic acid in a solution which also contains hydrogen peroxide. A potential is applied between a reference electrode (120, 120′) and a working electrode (118, 118′). A read voltage (FIG. 7) is selectively pulsed across a counter electrode (122, 122′) and the working electrode. The current flowing between the working electrode and the counter electrode is dependent on the peroxyacetic acid concentration in the solution (FIG. 6). By careful selection of the read voltage, the contribution of hydrogen peroxide to the current flow is virtually negligible. The sensor effectively measures peroxyacetic acid concentrations in the range generally employed in sterilization and disinfection baths (100-3000 ppm.).

Abstract: The present invention relates to a reference electrode for a potentiometric electrode system, characterized in that the junction in contact with a sample solution is enlarged and an ion-sensitive membrane containing an ion selective material as a protective membrane for the inner reference solution is employed, which comprises a substrate; a metal layer; an insoluble metal salt layer; an insulating film for insulating the metal layer from an aqueous solution; a hydrogel serving as an inner reference solution; the junction on the hydrogel contacting with a sample solution; the ion-sensitive, protective membrane formed over all surface areas of the hydrogel, except for the junction, to separate the sample solution from the inner reference solution or act as an ion-sensing membrane upon the contamination of the junction, whereby the operational abnormality caused by junction contamination may be easily checked and fast activation may be achieved.

Abstract: A method for measuring a target constituent of an electroplating solution using an electroanalytical technique is set forth in which the electroplating solution includes one or more constituents whose by-products skew an initial electrical response to an energy input of the electroanalytical technique. The method comprises a first step in which an electroanalytical measurement cycle of the target constituent is initiated by providing an energy input to a pair of electrodes disposed in the electroplating solution. The energy input to the pair of electrodes is provided for at least a predetermined time period corresponding to a time period in which the electroanalytical measurement cycle reaches a steady-state condition. In a subsequent step, an electroanalytical measurement of the energy output of the electroanalytical technique is taken after the electroanalytical measurement cycle has reached the steady-state condition.

Abstract: An ultraviolet light measuring chip and a sensor are provided simple in structure, easy to handle and of high precise measurement. The chip comprises a first reaction chamber for detection of total received light and a second reaction chamber for detection of ultraviolet-cut received light. The first and second chambers contain or hold therein counter and reference electrodes immersed in coexistent electrolyte solution containing quinone, organic solvent and electrolyte the solution being also contained the chambers. The first chamber has a total light transmission window and a first working electrode immersed in the electrolyte solution. The second chamber has an ultraviolet-cut light transmission window and a second working electrode immersed in the electrolyte solution. The sensor is adapted to sweep voltages of the first and second working electrodes to the respective reference electrodes, detect respective currents and calculate out an amount of ultraviolet light from difference of the detected currents.

Abstract: In a method and apparatus of an amperometric probe for characterization of the electrostatic state in gases containing ions, by means of the electrical space potential and/or the density of positive and negative ions, in particular in gases flowing around a sensor (1) with an applied electrical potential (5, 6), and emitting ions to the sensor; an electrical circuit (2) is provided for detecting the measured sensor curents; a current comparison unit (3) follows the current detection and monitors that the sensor currents are within the permissible value range in terms of their mathematical sign and their magnitude, applies a first sensor potential and detects the associated sensor current, as well as subsequently applies a second sensor potential and carries out an adaptation process in such a way that the detected second sensor current has the same mathematical sign as the first sensor current; the space potential and the density of the ions of one polarity are determined in a calculation unit (4); and, with

Abstract: This invention provides a gas sensor including a proton-conductive polymer electrolyte layer and a method for measuring gas concentration, that are capable of measuring gas concentration at high accuracy nothwithstanding the presence of water vapor.

Abstract: A system and method for reducing the number of input/output connections required to connect a microfluidic substrate to an external controller for controlling the substrate. In one example, a microfluidic processing device is fabricated on a substrate having a plurality of N independently controllable components, (e.g., a resistive heating elements) each having at least two terminals. The substrate includes a plurality of input/output contacts for connecting the substrate to an external controller, and a plurality of leads for connecting the contacts to the terminals of the components. The leads are arranged to allow the external controller to supply control signals to the terminals of the components via the contacts using substantially fewer contacts than the total number of component terminals.

Abstract: An ultramicroelectrode is disclosed which includes a) a silicon substrate; b) a silicon oxide insulating layer; c) a titanium adhesion layer; d) an iridium layer; e) a gold bond pad layer; f) a titanium adhesion layer; and g) a silicon dioxide insulating layer. In a preferred embodiment, the f) and g) layers have been partially or totally removed. Preferably, the ultramicroelectrode of the invention does not include mercury.

Abstract: Electrokinetic devices having a computer for correcting for electrokinetic effects are provided. Methods of correcting for electrokinetic effects by establishing the velocity of reactants and products in a reaction in electrokinetic microfluidic devices are also provided. These microfluidic devices can have substrates with channels, depressions, and/or wells for moving, mixing and monitoring precise amounts of analyte fluids.

Abstract: A method and device for the detection of substances such as nitrotoluene, trinitrotoluene, dinitrotoluene, or derivatives, wherein a working electrode and an opposing electrode are contacted with the substance via a viscous electrolyte layer and a voltage is applied to the working electrode whose value is increased and decreased at least once with substantially equal beginning and end values within a predetermined time period, wherein the current strength is determined during this at least one measurement cycle in dependence on the applied voltage, is distinguished in that a plurality of measurement cycles are scanned, and differences of current values of sequential measurement cycles are determined and, in the event of the occurrence of a cathode current maximum, the associated voltage value is determined, held constant and the current strength extracted.

Abstract: In an improved amperometric gas sensor, the structure, composition, and electrode potential are adjusted so as to prevent or minimize any unwanted reactivity at the counter and/or reference electrode of any analyte or interfering component of the matrix that may cross over thereto. The sensor is preferably structured so that the product of the analyte reaction at a first working electrode can be reconverted to the original analyte at a counter electrode or at a second working electrode and then reacted again at the first working electrode, with such back-and-forth reactions repeating many times, so as to yield an amplification of the analyte signal.

Abstract: Emission of NOx during acid-piclding treatment of metals in an aqueous solution containing at least nitric acid is controlled by the addition of hydrogen peroxide. The addition amount of hydrogen peroxide is minimized to avoid excessive addition by monitoring the potentiostatic electrolytic current of the solution or by combinedly monitoring the potentiostatic electrolytic current and the redox potential of the solution.

Abstract: An apparatus and method for identifying and/or quantifying a charged biological substance in a conductive liquid medium.

Abstract: An electronic tongue for the detection of ozone is based on voltammetry, and comprises at least one working electrode and a counter electrode, wherein the working electrode(s) is(are) made of one or more transition metals or Au, or alloys thereof, or alloys thereof with other metals. The data processing is made by multivariate analysis. The sensor can be implemented on-line or in-line in a processing plant where it is desirable to monitor and control ozone levels, e.g. sterilization and purification plants.

Abstract: An amperometric electrochemical gas sensor includes a permanent electrical resistance means disposed between two electrodes, one of which is the working electrode, the electrical resistance means having an electrical resistance of between about 10&OHgr; and 200 k&OHgr;. This resistance means provides a permanent shorting link between the electrodes, and constantly maintains the sensor in a ready-to-work condition.

Abstract: A gas sensor is described which is particularly well suited as a carbon monoxide (CO) sensor in a self test gas sensor. The sensor includes a number of aspects which may or may not be used in conjunction with one another. A first aspect is an embodiment which reduces electrical interference (or cross-talk) between a test or gas generating cell and a sensing cell. In one embodiment, baffles are provided to prevent cross-talk. In another embodiment a switching circuit ensures that a test gas generator is operational only when the gas sensor is disconnected from a current source. A second aspect is an embodiment which includes an improved wick which is in close proximity with an electrode and ensures electrolyte is always in contact with the electrode. In an alternate embodiment a solid polymer electrolyte is used between the electrodes. A third aspect is an improved catalyst which reduces the reaction energy and thereby renders the sensor more sensitive. The catalyst is also cheaper than platinum.

Abstract: A biologic electrode array is formed on a semiconductor substrate. A matrix of electrode sites is disposed on the semiconductor substrate. A matrix of optical detectors is disposed beneath the electrode sites in the semiconductor substrate, wherein each electrode site is associated with a corresponding optical detector. The optical detectors are coupled to detection circuitry formed on the semiconductor substrate. The electrode sites may include slitted electrodes, punctuated electrodes, or optically transparent electrodes.

Abstract: A method of addressing and driving an electrode array includes the step of addressing one or more electrodes within the array using a plurality of row and column lines. In one aspect of the method, a value corresponding to a voltage is stored in a local memory associated with each electrode. The addressed electrodes are then driven at the voltages corresponding to the stored values. In another aspect of the method, a driving element associated with each addressed electrode is selectively coupled with a voltage line so as to charge the electrode with the voltage on the voltage line. The device and methods may be used in the synthesis of biopolymers such as oligonucleotides and peptides.

Abstract: In a method and an apparatus for measuring a concentration of at least one dissolved chemical entity in a liquid medium, employing a counter electrode, a working electrode and a reference electrode immersed in the liquid medium, at least one measurement potential is applied to the working electrode relative to the reference electrode, corresponding to a measurement voltage during at least a part of a measurement period, thereby causing the dissolved chemical entity to participate in an electrochemical reaction at the working electrode, the chemical reaction resulting in a measurement evoked current. Compensation for potential drift at the reference electrode is achieved by comparing the measurement evoked current with a predetermined value, and decreasing or increasing the measurement voltage by an incremental value, in a negative or a positive incremental step, so that the measurement current approaches a predetermined value.

Abstract: An amperometric electrochemical gas sensor includes a permanent electrical resistance means disposed between two electrodes, one of which is the working electrode, the electrical resistance means having an electrical resistance of between about 10 &OHgr; and 200 k&OHgr;. This resistance means provides a permanent shorting link between the electrodes, and constantly maintains the sensor in a ready-to-work condition.

Abstract: A sensor for identifying molecular structures within a sample solution is disclosed. The sensor comprises an insulating layer with a plurality of interspaced channels therein having essentially the same direction. The channels furthermore have submicron dimensions. A method of fabricating a sensor for identifying molecular structures within a sample solution is also disclosed.

Abstract: A electrochemical sensor for the detection of traces of HF and/or other acid gases in air, comprising a measuring electrode of an electrochemically active metal oxide powder, a reference electrode for fixing the potential of the measuring electrode close to the equilibrium potential of the oxidation/reduction system of MeOn/Mem+, and a counter electrode. The electrodes are in communicative contact with a hygroscopic electrolyte. The measured gas component changes the pH of the electrolyte, and thus the electrochemical equilibrium of the measuring electrode, to produce a measurable electrical current that is proportional to the concentration of the detected acid gas.

Abstract: A sensor array for detecting the distribution of fluids having different electrical characteristics, comprising a multilayer structure including a first layer which defines an array of spaced apart sensor electrodes, a second layer separated from the first layer by dielectric material and defining a conductive screen, and a third layer separated from the second layer by dielectric material and defining a series of spaced apart elongate connections, each sensor being connected to a respective connection by a respective conductive path extending through an opening in the conductive screen defined by the second layer.

Abstract: The Applicant's invention comprises an apparatus and method for determining the amount of one or more components in a pulping liquor. At a first electrode, a varying voltage is supplied in a voltage range including the half-wave potential of each component of a liquor to be measured, and accounting for variations in the half-wave potential caused by changing process parameters. At a second electrode, which is roughly ⅓ to ¼ the size of the first electrode, the derivative of current intensity is monitored near the known half-wave potential for the various liquor components. Using curve-fitting means, the derivative of current intensity and selected other process condition data is used to determine concentrations of the various liquor components.

Abstract: A digital electrochemical sensor is provided with a sensor electrode array (1-4) and an operating electronic unit integrated on a chip for processing electrical signals received therefrom. The operating electronic unit includes a potentiostat circuit and a microprocessor, which receives and further processes the signals processed by the operating electronic unit. To provide an electrochemical sensor which can be operated more simply and with higher precision during installation and in operation the potentiostat circuit is a digital circuit, whose controller function is controlled by the microprocessor (20), and for the microprocessor (20) to be also integrated on the chip of the operating electronic unit.

Abstract: An analytical or preparatory system comprised as a base unit, an adapter, and a substrate. The adapter is attached to an attachment region on the base unit, and the substrate is attached to an attachment region on the adapter. The adapter permits the base unit to be interfaced with a wide variety of different substrates to perform chemical and biological analytical analyses and preparatory procedures. An interface array is disposed upon the adapter. The interface array contains electrical pins, electrical contacts or electrical contact pads that directly engage fluid containing reservoirs disposed on a microfluidic device and which are coupled to a power supply.

Abstract: The time profile of the output signal of an NOx measurement transducer arranged downstream of the NOx storage catalyst is used, during and after the regeneration phase, to derive a criterion as to whether the quantity of regeneration agent to be supplied to the NOx storage catalyst in a regeneration phase must be changed in order to achieve an optimum action of the exhaust-gas purification system. The output signal is picked off at the amperometric NOx measurement transducer at two electrodes. The measurement transducer exhibits the two-position behavior necessary for the method.

Abstract: An adjustment circuit and method for reading a measurement output of an automotive oxygen sensor provide correction for outgassing of the sensor and inversion of the measurement output. The adjustment circuit includes a biasing stage connected to a sensor return of the oxygen sensor, where the biasing stage applies a predetermined bias voltage to the sensor return. An input stage is connected to an output of the sensor for retrieving the measurement output from the sensor. The adjustment circuit further includes an A/D conversion system connected to the input stage for adjusting the measurement output based on the bias voltage. The A/D conversion system may further be connected to the biasing stage for retrieving a sensor return output from the sensor. In such cases, a differential module calculates a difference between the sensor return output and the measurement output. The sensor return output defines an actual bias voltage applied to the sensor return.

Abstract: An electrochemical measuring cell for detecting hydrocyanic acid is improved in such a manner that a stable measurement signal is provided after a short time. The measuring cell includes a measuring electrode (1) of sintered gold and a counter electrode (2). A measuring cell housing (4) accommodates the measuring electrode (1) and the counter electrode (2). An electrolyte is in the measuring cell housing (4) and includes sulphuric acid with an additive of silver sulphate. A diffusion membrane (5) is disposed between the measuring electrode (1) and the substance to be detected.

Abstract: A method for measuring a target constituent of an electroplating solution using an electroanalytical technique is set forth in which the electroplating solution includes one or more constituents whose by-products skew an initial electrical response to an energy input of the electroanalytical technique. The method comprises a first step in which an electroanalytical measurement cycle of the target constituent is initiated by providing an energy input to a pair of electrodes disposed in the electroplating solution. The energy input to the pair of electrodes is provided for at least a predetermined time period corresponding to a time period in which the electroanalytical measurement cycle reaches a steady-state condition. In a subsequent step, an electroanalytical measurement of the energy output of the electroanalytical technique is taken after the electroanalytical measurement cycle has reached the steady-state condition.

Abstract: A sensor (1) for measuring O2 concentrations in liquids (2) has a working electrode (3), with a counterelectrode (4) and with a reference electrode (5), wherein the working electrode (3) and the counterelectrode (4) are in contact with the liquid (2). The reference electrode (5) is separated from the liquid (2) by a diaphragm (6). The reference electrode (5) measures a polarization voltage effectively acting at the working electrode (3) and is connected to a potentiostat regulating the potential between the working electrode (3) and the counterelectrode (4). The reference electrode (5), the working electrode (3) and the counterelectrode (4) are arranged coaxially to one another, wherein the working electrode (3) and the counterelectrode (4) are arranged around the reference electrode (5).

Abstract: Electrochemical sensor for determining analyte in the presence of interferent, particularly carbon monoxide in the presence of hydrogen. An electrochemical cell is designed so that current flow resulting from reference electrode potential shift caused by interferent cancels out the current flow caused by interferent at the working electrode. Another electrochemical cell corrects for interferent concentration using the potential difference between a reference electrode in contact with interferent and a referent electrode not affected by inteferent.

Abstract: Disclosed is a porous membrane built-in biosensor comprising (a) at least one substrate; (b) an electrode layer patterned on the substrate, consisting of an electrode system and a circuit connector; (c) an insulator, formed on parts of the electrode layer, for electrically separating the electrode system from a circuit connector; and (d) a porous membrane via the insulator on the electrode system, wherein, when a whole blood sample is introduced to the biosensor, the whole blood sample is separated into its components during the chromatographic motion through the porous membrane so that only blood plasma can be contacted with the electrode system. The porous membrane built-in biosensor is provided with a sample inlet, which allows samples to be introduced in a constant quantity to the biosensors porous membranes without pretreatment.

Abstract: This invention relates to a low impedance cell potential measuring electrode assembly typically having a number of microelectrodes on an insulating substrate and having a wall enclosing the region including the microelectrodes. The device is capable of measuring electrophysiological activities of a monitored sample using the microelectrodes while cultivating those cells or tissues in the in the region of the microelectrodes. The invention utilizes independent reference electrodes to lower the impedance of the overall system and to therefore lower the noise often inherent in the measured data. Optimally the microelectrodes are enclosed by a physical wall used for controlling the atmosphere around the monitored sample.